1. Field of the Invention
The present invention relates to fuels for internal combustion engines and, more particularly, to such fuels containing an additive ingredient which significantly improves the operating economy and performance of compression ignition (diesel) engines.
2. Description of the Prior Art
Almost from the inception of the internal combustion engine and certainly from the time of its widespread use, numerous proposals have been advanced for improving one or another performance characteristic of the engine by incorporating one or more additives in the hydrocarbon fuels used in its operation. Among such additives have been various nitro-containing organic compounds, sometimes used for the purpose of increasing the energy content of the fuels and at other times used for the purpose of improving the ignition characteristics of the fuels. German Patent No. 164,634 (1903) discloses gasoline to which has been added as an energy booster, a nitro compound such as dinitronaphthalene, nitronaphthol, nitroglycerine or picric acid (trinitrophenol). Eckart, Brennstaff-Chemie, No. 9. pp. 134-136 (1923) discloses gasoline fuels for racing engines which contain such energy-rich materials as the nitrobenzenes, nitroglycerine, nitronaphthol, dinitronaphthalene, dinitrotoluene and dinitrocellulose in amounts of up to 5%. Similarly, United Kingdom Patent No. 131,869 (1918) proposes the use of a nitro derivative of benzole, toluene, xylol, naphthalene or aniline in such liquid or gaseous combustibles as benzole, petrol, oil, heavy oils, naphtha, and the like.
Specifically with regard to fuels for compression ignition, or diesel, engines, U.S. Pat. No. 1,849,051 (1932) describes the addition of a nitro-containing primer composition to accelerate ignition (i.e., increase the cetane rating) of the fuels. The primer can be trinitrophenol, dinitrophenol, dinitrobenzene, trinitroglycerine or trinitrotoluene. U.S. Pat. No. 2,251,156 (1941) describes a diesel fuel of improved ignition quality containing a nitro compound such as 4- nitro benzene diazo thiophenyl ether or 4-nitro benzene diazo hydrosulfide.